Realizing High-Efficiency Yellow Emission of Organic Antimony Halides via Rational Structural Design

Zero-dimensional (0D) organic metal halides have captured extensive attention for their various structures and distinguished optical characteristics. However, achieving efficient emission through rational crystal structure design remains a great challenge, and how the crystal structure affects the photophysical properties of 0D metal halides is currently unclear. Herein, a rational crystal structure regulation strategy in 0D Sb(III)-based metal halides is proposed to realize near-unity photoluminescence quantum yield (PLQY). Specifically, two 0D organic Sb(III)-based compounds with different coordination configurations, namely, (C₂₅H₂₂P)₂SbCl₅ and (C₂₅H₂₂P)SbCl₄ (C₂₅H₂₂P⁺ = benzyltriphenylphosphonium), were successfully obtained by precisely controlling the ratio of the initial raw materials. (C₂₅H₂₂P)₂SbCl₅ adopts an octahedral coordination geometry and shows highly efficient broadband yellow emission with a PLQY of 98.6%, while (C₂₅H₂₂P)SbCl₄ exhibits a seesaw-shaped [SbCl₄]^- cluster and does not emit light under photoexcitation. Theoretical calculations reveal that, by rationally controlling the coordination structure, the indirect bandgap of (C₂₅H₂₂P)SbCl₄ can be converted to the direct bandgap of (C₂₅H₂₂P)₂SbCl₅, thus ultimately boosting the emission intensity. Together with efficient emission and outstanding stability of (C₂₅H₂₂P)₂SbCl₅, a high-performance white-light emitting diode (WLED) with a high luminous efficiency of 31.2 lm W^-1 is demonstrated. Our findings provide a novel strategy to regulate the coordination structure of the crystals, so as to rationally optimize the luminescence properties of organic metal halides.